// stores the reference to the XMLHttpRequest object
var xmlHttp = createXmlHttpRequestObject();
// retrieves the XMLHttpRequest object
function createXmlHttpRequestObject() {
	// will store the reference to the XMLHttpRequest object
	var xmlHttp;
	// if running Internet Explorer
	if (window.ActiveXObject) {
		try {
			xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
		} catch (e) {
			xmlHttp = false;
		}
	}
	// if running Mozilla or other browsers
	else {
		try {
			xmlHttp = new XMLHttpRequest();
		} catch (e) {
			xmlHttp = false;
		}
	}
	// return the created object or display an error message
	if (!xmlHttp)
		alert("Error creating the XMLHttpRequest object.");
	else
		return xmlHttp;
}
// make asynchronous HTTP request using the XMLHttpRequest object
function process() {
	// proceed only if the xmlHttp object isn't busy
	if (xmlHttp.readyState == 4 || xmlHttp.readyState == 0) {
		// retrieve the name typed by the user on the form
		name = encodeURIComponent(document.getElementById("myName").value);
		// execute the quickstart.php page from the server
		xmlHttp.open("GET", "quickstart.php?name=" + name, true);
		// define the method to handle server responses
		xmlHttp.onreadystatechange = handleServerResponse;
		// make the server request
		xmlHttp.send(null);
	} else
		// if the connection is busy, try again after one second
		setTimeout('process()', 1000);
}
// executed automatically when a message is received from the server
function handleServerResponse() {
	// move forward only if the transaction has completed
	if (xmlHttp.readyState == 4) {
		// status of 200 indicates the transaction completed successfully
		if (xmlHttp.status == 200) {
			// extract the XML retrieved from the server
			xmlResponse = xmlHttp.responseXML;
			// obtain the document element (the root element) of the XML
			// structure
			xmlDocumentElement = xmlResponse.documentElement;
			// get the text message, which is in the first child of
			// the the document element
			helloMessage = xmlDocumentElement.firstChild.data;
			// update the client display using the data received from the server
			document.getElementById("divMessage").innerHTML = '<i>'
					+ helloMessage + '</i>';
			// restart sequence
			setTimeout('process()', 1000);
		}
		// a HTTP status different than 200 signals an error
		else {
			alert("There was a problem accessing the server: "
					+ xmlHttp.statusText);
		}
	}
}